Has the Meridian 206DS output caps?

[spendorspain]

Hi,

I own a Meridian 206 Delta Sigma CD player (Crystal CS4328 chip) since 1993. It sounded and sounds today great
and I'm very satisfied with it.

I'm going to use my 206DS with a new headphone amplifier and I have to choose one of the two versions of the amp:
one with input capacitors (4.7uF polypropylene) and other (better
sounding) without these input caps. I need to know if
the Meridian 206Delta Sigma CD player has DC blocking output
capacitors, like many others CD players, or not.

If I can confirm that the 206DS has output caps, I'll use
the capacitor-less version of the headphone amplifier,
the option I prefer. If not, I need to buy the other
version of the amp for safe use without the risk of
amplify any possible DC offset coming from 206DS
outputs.

I have searched in several forums and I've sent an e-mail to Meridian Audio without results, so I'd be very grateful if you could answer to my question, or give some advice on this
subject.

Regards
Jose

[quantran]

You can open the box to see if they use output cap. However some well designed CDPs/DACs output any significant DC even without output cap. You can use a vol meter to measure at the output.

[spendorspain]

Thanks Quan.

I must confess I can't open the lid of my Meridian 206 (I can't unscrew the screws that fix it to the back panel ... believe me, it's impossible). Therefore my question and my need of a schematic of 206 DeltaSigma output, if available.

Could you explain how to measure DC offset at RCA outputs of CD player with a multimeter? I suppose I have to touch the inner tube ("live") of RCA socket with the red probe and the outer "ring" ("ground") of socket with the black probe, with my multimeter set to measure mV DC (in my case in its "< 2V DC" setting ). And I have to do this in both channels without music playing (perhaps in "pause"). Is this correct?

What would be a safe value of DC offset, if present, in order to connect the CD player to an amplifier which has no input capacitors? This value can drift (e.g.: Can be a safe value today but larger and dangerous in other cincumstances?)

Thanks again. Regards
Jose

[soongsc]

Originally posted by spendorspain
Hi,

I have searched in several forums and I've sent an e-mail to Meridian Audio without results, so I'd be very grateful if you could answer to my question, or give some advice on this
subject.

Regards
Jose

If the Meridian 206 is not their current model on the market, I would think they would respond with the schematics. I had very good response from them. They even sent me a schematic of an old integrated amp I was trying to fix, for free!

[quantran]

You should measure in both directions because the DC offset can be positive or negative. The measurement should be done while the CDP is playing. If it has an output cap the result should be zero.

Originally posted by spendorspain
Could you explain how to measure DC offset at RCA outputs of CD player with a multimeter? I suppose I have to touch the inner tube ("live") of RCA socket with the red probe and the outer "ring" ("ground") of socket with the black probe, with my multimeter set to measure mV DC (in my case in its "< 2V DC" setting ). And I have to do this in both channels without music playing (perhaps in "pause"). Is this correct?

I can't comment on the exact value. However I don't think any reputable manufacturer will sell to its customer a CDP which outputs significant DC because most customers do not pay attention to this. If the CDP cause any damage to customers's system then the manufacturer would be in big troubles.

Originally posted by spendorspain

What would be a safe value of DC offset, if present, in order to connect the CD player to an amplifier which has no input capacitors? This value can drift (e.g.: Can be a safe value today but larger and dangerous in other cincumstances?)

[spendorspain]

Thank you for your comments.

I have just received the schematic from Meridian Audio (see image attached to this post) and I've measured the DC offset of my 206DS CD player.
I have read in my multimeter a DC voltage between 0.000 and 0.001 volts in both channels but I can't see an output capacitor in series with the RCA sockets to blocking DC.
I think 1mV is a very low offset, but I'm still concerned about the possibility of drifting in these values. What do you think about this?
Is there any situation that can induce an anormally increased DC offset? If so, what are the possible effects on the equiment connected to the CD player? (remember that the amplifier has no input capacitor)

Thanks again for your answers (and for your patient with this newbie
Regards
Jose

[quantran]

R85, R86, R87 and R88 are to adjust DC offset to near zero. That's why it does not need a capacitor.

If you put a DC into the amp input. This DC may be amplified and output to speakers/headphone. Large DC into speakers/headphone will damage them.

In your case the DC offset is quite low. That's is within Meridian intention in this design. It will not cause problems unless the CDP is deffective.

[soongsc]

Told you they provide good service.

[spendorspain]

Hi,

It seems I sent my first e-mail to the wrong place at Meridian Audio. I've just connected my 206DS CD player to my input capacitor-less headphone amp and it sounds great!.
Many thanks to all of you for your help

Regards
Jose

[ergo]

Just one point left to consider.

At switching the power on or off on Meridian might create momentary offset in output. This is the condition where power supply lines may start or drop differently and the output might have an offset !! But any good headphone should survive it without any damage.

Regards,
Ergo